I am finding the same problem as I source replacement parts for my rebuild. Also if you order from the US and they ship with UPS you can get hit with border crossing "brokerage fees" that will sometimes cost you more than the item you ordered.
Recently I discovered the solution. I happen to work in a border town (Cornwall, ON) and discovered a place across the border called The Ship-It Shop. For a small fee they will accept UPS deliveries for you and email you when they arrive. Fees are reasonable ($3 for small, $5 for large). When they email me it just costs me about another $2.75 bridge toll each way, 20 minute drive, and (possibly) taxes on the item at Canadian Customs.
I find the fees, and bridge toll to be way cheaper than just the extra shipping charges to Canada, let alone the "brokerage fees".
I've used them twice now ordering parts for my
Kegerator and a buddy of mine uses them almost monthly.
With them in mind I don't even bother trying to source parts in Canada unless it's something physically impossible to ship, or something I want to see in person before buying.
Hope this helps.